I'm not questioning what you are saying, but Wayland's only requirement is DRM, which is a Linux kernel capability that is supported for basically everything that you can push some sort of display cable into. It's for buffer management, and X was also ported to use this API.
Unless you have proprietary X server blobs, you have mostly the same low level route in either case to display stuff, so it's on the exact compositor you have tried, not on the wayland protocol.
I agree, it should work. It just doesn't. I haven't had the time yet to figure out why it doesn't because everything is fine on X11.